Field of the Invention
The present invention relates to improvements in an apparatus for laser beam treatment. More particularly the present invention relates to improvements to avoid possible danger to human eyes by an invisible laser beam in an apparatus for laser beam treatment.
Recently, many studies of medical treatments such as acupuncture or the like have been made. And among them, treatment of various aches such as toothache, lumbago, stiffness in the shoulders arms and legs, are made by use of a laser light beam. And recently, the relations between and effects of intensity, treating time, wavelength of light and repetition period of light beam pulses on such medical treatment are more and more made clear with respect to therapeutic effect. However, causality of photochemical effect of the laser beam on medical treatment has some unclear points. Many reports have been made concerning the application of a laser beam for medical treatment. But those reports dealing with operativity and safetyness for the apparatus of such medical treatment are not yet sufficient.
The laser light beam is different from an usual light beam, in that it is coherent light which can be easily focused. Accordingly, even when using a rather small laser light beam, of for instance several milliwatts, it is possible to obtain a very high power density of the light beam by effectively converging the light beam into a very small area, for instance, from several to less than one mm.sup.2. In medical treatment, usually a laser light having a wavelength range in the infrared light range is used, which is easily absorbed in human skin. Accordingly, when such invisible laser light erroneously enters human eyes because of a misoperation, then the retina of the eye may be easily destroyed to make the patient blind.